Buried pipes and cables are often protected by means of a warning tape, buried in the ground above the pipe or cable at a substantially lesser depth. The hope is that as someone is using a backhoe or the like to dig a trench, they will first encounter the warning tape and be thus warned to stop digging before damaging the pipe or cable.
The warning tapes of the prior art are made of plastic films, upon which printed indicia may be impressed. the printing typically carries a warning and may describe the type of cable or pipe which is underneath the tape. Several disadvantages of prior art buryable warning tapes include the fact that plastic films tend to have a fairly low tensile strength and a very low tear strength. Thus, a backhoe may cut through a warning tape of the prior art without the operator even noticing.
Furthermore, the visible indicia printed on the prior art fabric does not stand up well to underground conditions. The ink of the indicia is easily abraded off both in the installation of the warning tape, and also while being inadvertently dug out by a backhoe or the like. This is made worse by the fact that the ink is constantly subject to the moist conditions of the underground, so that its binder can deteriorate.
In accordance with this invention, a different type of buryable warning tape is provided, having greatly increased tensile and tear strength, and also greatly increased durability of visible indicia carried thereon, so that the warning provided by the tape is clearer and more reliable. The tape of this invention is strong enough so that when engaged by a backhoe, it can entangle the backhoe and be pulled out of the ground without breaking as the backhoe retracts in its digging motion. Thus the tape can make its presence known in a very obvious and tangible way to the operator of a digging machine, for improved protection of a cable or pipe underneath the warning tape. Additionally, the warning tape of this invention exhibits improved durability for the visible indicia carried thereon, so that even after years of burying, the tape can effectively perform its function.